Phenolic hyperbranched polymers as additives in cationic photopolymerization of epoxy systems

A phenolic group containing hyperbranched polyester was synthesised and employed as chain transfer agent in cationic photopolymerization of a bis -cycloaliphatic epoxy monomer (CE). The presence of such additive induces a change on the kinetics of photopolymerisation and of the properties of the cured films. The photocured films, in the presence of HBP, are characterized by a decrease of the Tg values together with an increase of the toughness properties. These results can be interpreted both on the basis of the flexibilization effect of HBP and on the increase of the final epoxy groups conversion and the high functionality of HBP. Therefore we have reached the interesting results of obtaining a decrease of the Tg value with an increase of the E’ value.